Fractional quantum Hall effect in organic molecular semiconductors.

High-quality crystals of the organic molecular semiconductors tetracene and pentacene were used to prepare metal-insulator-semiconductor (MIS) structures exhibiting hole and electron mobilities exceeding 10(4) square centimeters per volt per second. The carrier concentration in the channel region of these ambipolar field-effect devices was controlled by the applied gate voltage. Well-defined Shubnikov-de Haas oscillations and quantized Hall plateaus were observed for two-dimensional carrier densities in the range of 10(11) per square centimeter. Fractional quantum Hall states were observed in tetracene crystals at temperatures as high as approximately 2 kelvin.